The prior art contains many examples of protective headguard systems. The prior art describes a variety of fit and retention systems.
Headguard fit and retention systems are intended to keep the headgear on the head during use, maintain fit and comfort while in use, and allow the user to easily put on and take off the headgear when desired.
Fit and retention systems must deal with the basic characteristics of the human head: the generally spheroidal shape; the neck; and the various features such as the face, ears, frontal bone, occipital bone, or the parietal eminences.
Protective helmets use various means to improve retention and fit. For those with hard and stiff shells, compressible padding, padding inserts, and adjustable suspension are some of the means by which different head sizes can be accommodated. Football, hockey, bicycle helmets, and construction hard hats would fall into this category. For headgear with soft flexible shells, such as the headgear used in boxing, the martial arts, or soccer, the shape of the entire piece of headgear can be altered with, for example, adjustment straps to help conform it to the shape of the head.
In many instances, however, additional retention means such as chinstraps become necessary. Chinstraps typically attach near the edges of the helmet close to the ears and either pass under the chin or over the chin. A fastening system such as a buckle or snap allows the user to fasten and unfasten the chinstrap.
While chinstraps may help retain a helmet on the head, chinstraps can pose problems. First, chinstraps may heighten risk by increasing the rigidity of the head protection system. Forces applied to the head at angular vectors may cause the helmet and the head to rotate. Significant rotational forces can harm both the brain and the neck. An inflexible chinstrap therefore may contribute to injury by placing additional strain on the head as it rotates.
Second, chinstraps often require difficult and inconvenient adjustments for proper fit. In many instances such adjustments may be difficult and inconvenient. Third, chinstraps are often uncomfortable. Chinstraps that run over the chin usually require a cup to fit on the chin. A chin-cup may restrict the jaw and limit activities such as speech. Finally, even properly adjusted chinstraps may do little to prevent minor shifts in the helmet during normal use. These minor shifts can be very bothersome for activities, for example, that require unimpeded sight.
Various means have been attempted to improve fit and retention to overcome the shortcomings of systems that rely primarily on the chinstrap. Doing so often requires balancing fit, retention, and comfort. With almost any headgear, retention can be improved by simply making the headgear fit tighter. For headgear such as knit winter hats or winter headbands this does not typically pose a problem. A knit winter hat can fit relatively tight without causing discomfort. The lightness, elasticity, and conformability of such headgear are likely reasons for this.
For many kinds of protective headgear, however, creating a tighter fit merely results in discomfort. An American football helmet with a tight fit can be very uncomfortable. The bulk, inelasticity of the headgear structure, and the pressure points created where padding is compressed to fit variations on the head's surface could be causes for this.
Alternatives to simply tightening the fit have been developed. Many bicycle helmets, for example, have devices that cradle the occipital bone. These systems are not intended to eliminate the chinstrap but are intended to prevent minor shifts during normal use and to reserve the chinstrap for events such as accidents. These systems rely on a retention system that applies pressure to selected points on the head. In the case of the bicycle helmets with the occipital cradle, what amounts to a triangular retention system is created. In this system pressure is applied to a set of points below the occipital bone, points above the occipital bone, and points approximately in the middle of the forehead. However, these systems still rely on a chinstrap for retention purposes. Therefore there is still a pressure point under the chin.
U.S. Pat. No. 5,806,535 to Becker describes a head band with upper and lower bands continuously interconnecting along an entire circumference of a head.
International Patent No. PCT/KR03/001691 to Kim describes a head band with upper and lower bands episodically continuously interconnecting along an entire circumference of a head.
U.S. Pat. No. 6,397,399 to Lampe et al. teaches padding enclosed in a fabric covering. The fabric covering stretches to conform the padding to the head.
U.S. Pat. Nos. 6,266,827 and 6,349,416 to Lampe et al. reveal fit and retention systems with adjustment straps located in positions other than those where chinstraps would typically be located. Unlike a baseball cap, these devices may have two or more dependent circular lines of retention created by ribs which are fastened together in an overlapping position to conform to a human head.